1. Field of the Invention
The present invention relates generally to cross-connect systems for communications networks, and more particularly to interfaces used on opposite sides of a cross-connect switch for interfacing transmission links.
2. Description of the Related Art
In a cross-connect system, a plurality of incoming and outgoing interfaces are provided on opposite sides of a cross-connect switch for interfacing it to incoming and outgoing links. In a known cross-connect system for a synchronous network where STS-1 (synchronous transport signal level-1) and DS3 (digital signal-3) signals are inter-mixed, interfaces of different designs are used exclusively for STS-1 and DS3 signals. Specifically, the STS-1 interface for incoming links includes an STS-1 receive processor coupled to a corresponding STS-1 incoming link, and demapping circuit for extracting the DS3 signal which is stuffed into the payload of the STS-1 signal and a selector for coupling the STS-1 signal or the extracted payload signal to the cross-connect switch. The STS-1 interface for outgoing links includes a mapping circuit for providing payload mapping of an incoming DS3 signal for packing it into the payload of the STS-1 format and a selector for coupling the payload signal or an incoming STS-1 signal to an STS-1 transmit processor which is connected to a corresponding STS-1 outgoing link. The DS3 incoming interface includes a DS3 receive processor connected between a corresponding DS3 incoming link and the cross-connect switch, and the DS3 outgoing interface includes a DS3 transmit processor connected between the cross-connect switch and a corresponding DS3 outgoing link.
Because of the exclusive designs, the number of interfaces must be determined according to their types and traffic needs. It has been desired to provide interfaces that give flexibility in designing a network.